Computers and other like devices can be interconnected in a variety of ways to allow data to be communicated between them. One of the most common ways to provide such data communication is through a wired network. Wired networks, such as, e.g., wide area networks (WANs) and local area networks (LANS) tend to have a high bandwidth and therefore can be configured to carry digital data at high data rates. One obvious drawback to wired networks is that a user's movement is constrained since the computer needs to be physically connected to the network. Thus, for example, a user of a portable computer will need to remain near to a wired network junction to stay connected to the wired network.
An alternative to wired networks is a wireless network that is configured to support similar data communications but in a more accommodating manner. Here, the user of a portable device will be free to move around a region that is supported by the wireless network. A well known example of a wireless network is a cellular telephone network. Indeed, in the past, cellular telephone modems have proven popular for use with portable laptop computers and other like devices, despite their relatively low bandwidth.
In the future it is expected that higher bandwidth wireless networks will become more popular, especially in creating metropolitan area networks (MANs) in which users, i.e., subscribers, have the ability to freely move their portable communicating devices around within a coverage area. Many conventional wireless communication systems and networks tend to use omni-directional antennas to transmit and receive data packets, for example, from a router to a subscriber's device. Being omni-directional, however, such transmissions may interfere with or otherwise restrict the use of other communicating devices that operate in the same frequency band.
Recent improvements to the wireless network sector include the use of smart antennas that are capable of transmitting directed beams to one or more receiving devices (e.g., client devices). One example of a smart antenna based wireless network can be seen in the improved packet switched wireless data communication system described in U.S. Pat. No. 6,611,231, issued Aug. 26, 2003 and titled “Wireless Packet Switched Communication Systems And Networks Using Adaptively Steered Antenna Arrays”. Here, for example, a base station (e.g., access point) includes a phased array antenna panel that is configured to transmit a main beam to a client device. The main beam may also have one or more side-lobes as is well understood in the art. The smart antenna in this example may also be configured to receive signals transmitted from the client device.
The above exemplary wireless communication system can be adapted for various different types of communication protocols and/or standards. Currently, a very popular form of wireless communication includes the IEEE 802.11 family of protocols/standards. As currently implemented, these protocols/standards require the receiving device to associate with an access point during initialization, and/or when otherwise deemed necessary. The association process essentially establishes the communication link by having the receiving device detect the presence of available access points, determine which access point is probably the best candidate, attempt to associate with this “best candidate”, and if accepted by the best candidate access point, then communicate with that access point. If the receiving device is mobile and subsequently moves out of the coverage area of the access point to which it is associated, then there are provisions in the protocols/standards for the receiving device to attempt to associate with another available access point. This type of re-association process tends to work well for access points that utilize conventional omni-directional or broad beam antennas. However, for wireless communication systems that use smart antennas that produce significantly more narrow and directed beams, the receiving device may not always be able to determine when it should switch its association from one beam to another beam. One potential reason for this is that the receiving device may have moved into an area that is covered by a side lobe of the main intended beam. While the receiving device and access point may be able to continue to communicate via a side lobe in certain situations, it will usually be more preferable for the receiving device to re-associate with another intended main beam that provides coverage to the new location of the receiving device. Indeed, in certain situations, there may be a regulatory need for the receiving device to re-associate with a different intended main beam. For example, under certain regulatory schemes, the narrower point-to-point main beam from a smart antenna arrangement can be transmitted with significantly greater power than would be allowed for a point-to-multipoint omni-directional antenna arrangement.
Consequently, there is a need to for methods and apparatuses that will effectively cause a receiving device to switch beam association within a smart antenna based wireless communication system at selected times.